Alert archive / Colorado / Flash Flood Warnings in 2023

Flash Flood Warning 4, NWS Grand Junction, CO

August 2, 2023Eagle County, Garfield County, Pitkin County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Aug 2, 2023, 9:58 PM MDT for Eagle County, Garfield County, Pitkin County, Colorado. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 2, 2023, 9:58 PM MDT (03:58 UTC)
Expired: Aug 3, 2023, 12:26 AM MDT
In force: 2 hr
Issued by: NWS Grand Junction, CO
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Eagle County, CO, Garfield County, CO, Pitkin County, CO

The radar

The Grand Junction radar (KGJX), 101 km from the middle of the area, began a volume at 04:02 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Grand Junction, CO (KGJT), launched 00:00Z, 4.0 hours before the alert went out and 121 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 798 J/kg
Mixed-layer CIN: -64 J/kg
Mixed-layer LCL: 2314 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 145 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.9

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Grand Junction, CO wrote its last area forecast discussion before this flash flood warning went out at Aug 2, 5:37 PM MDT, 4 hours 21 minutes earlier.

Area forecast discussion, Aug 2, 5:37 PM MDT, 4 hours 21 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Hazardous weather outlook, Aug 2, 2:39 AM MDT, 19 hours 19 minutes before

Hazardous Weather Outlook
National Weather Service Grand Junction CO
239 AM MDT Wed Aug 2 2023

COZ001>014-017>023-UTZ022>025-027>029-030845-
Lower Yampa River Basin-Central Yampa River Basin-
Roan and Tavaputs Plateaus-Elkhead and Park Mountains-
Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor-
Central Colorado River Basin-Grand and Battlement Mesas-
Gore and Elk Mountains/Central Mountain Valleys-
Central Gunnison and Uncompahgre River Basin-
West Elk and Sawatch Mountains-Flat Tops-
Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide-
Northwest San Juan Mountains-Southwest San Juan Mountains-
Paradox Valley/Lower Dolores River-
Four Corners/Upper Dolores River-Animas River Basin-
San Juan River Basin-Southeast Utah-Eastern Uinta Mountains-
Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat-
La Sal and Abajo Mountains-Canyonlands/Natural Bridges-
239 AM MDT Wed Aug 2 2023

This hazardous weather outlook is for eastern Utah and western
Colorado.

.DAY ONE...Today and Tonight

Today will be the last day of truly monsoon like convection, with
heavy rain and frequent lightning still the main threats, followed
by small hail and gusty winds. Rainfall rates in excess of an inch
an hour are possible. As with the last several days, activity will
last well into the overnight.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Drier air begins to work in on Thursday, decreasing shower and
storm coverage somewhat. It will also lead to a transition away
from heavy rain producing storms to storms more likely to produce
gusty outflow winds. Frequent lightning remains a threat with any
storm. Temperatures will also begin to slowly warm to near or a
few degrees above normal by the weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

In the hours before

Special weather statement, Aug 2, 4:14 PM MDT, 5 hours 44 minutes before

Special Weather Statement
National Weather Service Grand Junction CO
414 PM MDT Wed Aug 2 2023

UTZ029-022245-
Canyonlands/Natural Bridges UT-
414 PM MDT Wed Aug 2 2023

...A strong thunderstorm will impact portions of southwestern San
Juan County through 445 PM MDT...

At 414 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles east of Halls Crossing, moving northeast at 35 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This storm will remain over mainly rural areas of southwestern San
Juan County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3745 11053 3753 11053 3769 11029 3739 11010
      3732 11053 3737 11061 3745 11062
TIME...MOT...LOC 2214Z 234DEG 32KT 3743 11050

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

ERW

Special weather statement, Aug 2, 4:46 PM MDT, 5 hours 12 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Local storm report, Aug 2, 4:59 PM MDT, 4 hours 59 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special weather statement, Aug 2, 5:15 PM MDT, 4 hours 43 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special weather statement, Aug 2, 5:26 PM MDT, 4 hours 32 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Special weather statement, Aug 2, 5:51 PM MDT, 4 hours 7 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

The office that day

Everything else NWS Grand Junction, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 2, 6:51 PM MDT	Special Weather Statement	GJT	Montezuma	24 min
Aug 2, 6:53 PM MDT	Special Weather Statement	GJT	Mesa	52 min
Aug 2, 7:19 PM MDT	Special Weather Statement	GJT	Rio Blanco	41 min
Aug 2, 7:24 PM MDT	Special Weather Statement	GJT	Dolores, Montezuma, Montrose, San Miguel	36 min
Aug 2, 7:48 PM MDT	Special Weather Statement	GJT	Delta, Garfield	42 min
Aug 2, 8:01 PM MDT	Special Weather Statement	GJT	Moffat	29 min
Aug 2, 8:40 PM MDT	Special Weather Statement	GJT	Garfield	35 min
Aug 2, 8:44 PM MDT	Special Weather Statement	GJT	Moffat	31 min
Aug 2, 9:08 PM MDT	Severe Thunderstorm Warning	GJT	Moffat, Routt	52 min
Aug 2, 10:50 PM MDT	Special Weather Statement	GJT	Eagle	25 min
Aug 3, 1:05 PM MDT	Special Weather Statement	GJT	Rio Blanco	25 min
Aug 3, 2:12 PM MDT	Special Weather Statement	GJT	Rio Blanco	33 min
Aug 3, 3:02 PM MDT	Special Weather Statement	GJT	Routt	28 min
Aug 3, 4:01 PM MDT	Special Weather Statement	GJT		29 min
Aug 3, 5:54 PM MDT	Special Weather Statement	GJT	Mesa	36 min
Aug 2, 6:01 PM MDT	Special Weather Statement	GJT	Uintah	29 min
Aug 2, 6:02 PM MDT	Areal Flood Advisory	GJT	Grand, San Juan	118 min
Aug 3, 3:50 PM MDT	Special Weather Statement	GJT	Grand	40 min
Aug 3, 4:30 PM MDT	Severe Thunderstorm Warning	GJT	Grand	45 min

Nearby

Flash Flood Warnings in Colorado, 2023 Every flash flood warning in 2023

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.